Strata hardness sensing device



Nov. 1, 1966 v. H. GARMONG ETAL 3,282,039

STRATA HARDNESS SENSING DEVICE 2 Sheets-Sheet 1 Filed Dec. 16, 1963 ww mm um Om INVENTORS VICTOR HQARMONQ JOHN H- W G BY O w MWLWUL ATTORNEY Nov. 1, 1966 v. H. GARMONG ETAL 3,282,039

STRATA HARDNESS SENSING DEVICE 2 Sheets-Sheet 2 Filed Dec. 16, 1965 INVENTORS V\CTOR H-G sf JOHN H.WAGNER BY I 94 90 ROCK F|g.5.

COAL

J W W ATTORNEY AL co COAL FIRE E CLAY COAL ROCK

United States Patent pany, Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 16, 1963, Ser. No. 330,699 17 Claims. or. 7378) This invention relates to a mining apparatus and more particularly to a new and improved continuously responsive strata hardness sensing means for a remotely controlled bore type mining machine.

In the field of remote controlled continuous mining machines, it has been the general practice to employ means for continuously indicating at the control station the relative hardness of the strata being cut so that the operator may guide the machine to cut in a selected sea-m, such as coal, for example, as opposed to rock or fire clay. Such devices normally include a strata cutting bit mounted on a boring arm, an electrical means to convert mechanical movements of the bit into electrical impulses, a suitable electrical circuit for transmitting such impulses to the control station and an oscilloscope for translating the electrical impulses into a pattern of visual signals.

Although such devices have served the purpose for which they were designed, they have not been entirely successful in all conditions of operation for the following reasons. Such prior known devices contained a multitude of moving parts such as couplings or linkages which wouldpact and simple in construction requiring a minimum amount of parts, reliable in operation and easy to manufacture. In addition, the sensing device comprises novel means for obtaining a more reliable and a more clear indication of the various earth strata .to provide a reliable guide for directing the course of the machine in any desired strata from a remote station outside the bore hole.

Accordingly, it is an object of the present invention to provide a new and improved strata sensing device for a remote control continuous mining machine.

Another object of this invention is -to provide a new and improved strata sensing device for a remote controlled continuous miner which is compact and simple in construction, requires a minimum amount of parts, is reliable in operation and easy to manufacture.

A specific object of this invention is to provide a new and improved strata sensing device having stop means for obtaining consecutive but diiferent rates of deflection change.

Another specific object of this invention is to provide a new and improved strata sensing device having stop means for obtaining three distinct ranges of sensitivity of strata indication as reproduced on an oscilloscope screen.

Still another specific object of this invention is to provide a new and improved strata sensing device having stop means for obtaining a reliable and sensitive distinction between coal, fire clay and rock.

A more specific object of this invention is to provide a new and improved strata sensing device having stop means for strengthening the lever arm of a sensing block to effect decreasing rates of deflection change of said lever arm for a given rate of force change and to enable a larger image of strata hardness indication to be reproduced on an oscilloscope screen.

These and other objects and advantages of the strata sensing device of this invention will become more readily apparent upon further consideration of the following description and drawings in which:

FIG. 1 is a side elevational view of a strata sensing block constructed in accordance with the principles of this invention with portions thereof broken away to more clearly show the structure thereof;

FIG. 2 is a front elevational view of the strata sensing block as shown in FIG. 1;

FIG. 3 is a cross-sectional view of a portion of the sensing block taken on lines 3-3 of FIGURE 2;

FIG. 4 is a plan view of the sensing block showing such sensing block mounted onto a boring arm of a continuous mining machine;

FIG. 5 is a circuit diagram of the transducer and oscilloscope electrical system; and

FIG. 6 is an oscill-ogr'am of the various earth strata encountered showing a comparison of the image produced on the screen of an oscilloscope by the old sensing device and the new and improved device.

Referring to the drawings and particularly to FIG. 1, it will be noted that a strata sensing device constructed in accordance with the principles of the invention comprises -a housing or strata sensing block 2 suitably secured to free end portion or outer reach of a boring arm 4 as by means of an elongated cylindrical metallic pin member 6. A .tapered cutter bit 8 is rigidly mounted in a transverse tapered opening it located inwardly adjacent a forward face 12 of block 2. For purposes of this description the forward direction is taken to be the righthand side of FIGURE 1 and 3 and the directions rearward, upper and lower will be referenced thereto. It is to be noted that these directions are used in this description purely for purposes of simplification and should not be applied as limiting this invention.

A slot 14 having opposed upper and lower surfaces 15 and 17, respectively, located below cutter bit 8 in block 2 extends parallel to the longitudinal axis of block 2 and axially inwardly from face 12. Slot 14 separates the forward end of block 2 into an upper portion 20 and lower portion 22. Received within slot 14 are an upper, formed, metallic plate 18 and a lower, formed, metallic plate 16.

Upper plate 18 has a bottom face 19 which is recessed inwardly adjacent the forward end thereof to provide a depression 24 having a surface 25 for a purpose hereinafter more fully explained. A depression 26 on bottom face 19 is located axially rearwardly of depression 24- and depression 28 is located inwardly adjacent the rearward end of upper plate 18. Lower :plate 15 has an upper face 30 which is provided with depressions 32 and 34- dis'posed in alignment or vertical registry with depressions 26 and 28, respectively. Lower plate 16 has a transverse bore 36 disposed in alignment or vertical registry with depression 24 extending from its upper face to its bottom face for receiving a portion of a transducer as hereinafter more fully explained.

As cutting loads are applied to the cutter bit by the resistance of the earth strata, the resulting forces are transmitted to the upper portion 20 of block 2 causing a bending moment of said upper portion. For the purpose of effecting different rates of deflection change, stop means are provided which act as fulcrum points about which upper portion 21) of block 2 will bend. Such means comprise a solid metallic stop 38 having a convex outer surface 40 suitably fitted in depression 28 and a solid metallic stop 41 having a concave outer surface 42 complementary to surface 40' is suitably fitted in depression 34. By providing arcuate shaped mating surfaces on the stops, a

substantially full surface area contact will be insured. Between surfaces 4-0 and 42 of stops 28 and 34 respectively, is a small air gap, for example, in the order of .001 of an inch. Similarly, stop 44 having a convex outer surface 46 is suitably fitted in depression 26 while stop 48 having a concave outer surface 50 complementary to surface 46 is suitably fitted in depression 32. The gap between surfaces 46 and 50 of stops 44 and 48 respectively, is approximately twice as large as the other, or about .002 of an inch. As cutting loads are applied to the bit 8, portion 20 will initially bend about the left end of slot 14, then about stops 28 and 34 and finally about stops 44 and-48. Thus, as the cutting loads increase, the stops located iat two different positions act as fulcrum points to shorten the moment arm in steps and thereby provide strength by decreasing the lever arm and effect a decreasing rate of deflection change for a given rate of load or force change.

A transverse bore 60 extending from surface 17 of slot 14 is located inwardly adjacent face 12 and is suitably counterbored at 61 to provide a shoulder 62. Suitably, releasably secured in bore 61 is a transducer 64 having a flange 66 which abuts shoulder 62 so that the transducer face 65 is spaced a predetermined amount from surface 25. The rear end of the transducer is supported by a set screw 68 which is engaged by cap screw 70. An elongated conduit 71 extending parallel to the longitudinal axis of block 2 is provided in block 2 to accommodate suitable conductors 74, 76 suitably electrically connected to transducer 64.

In order to prevent dirt, grit and moisture from entering into the spaces between the stops and between transducer 64 and surface 25, a seal 52 of resilient, bondable material, such as neoprene for example, is bonded between the plates 16 and 18 to completely envelope the stops and transducer except for the space between the contact surface areas of the stops, respectively, and the space between transducer face 65 and surface 25. This arrangement furthermore provides an integral assembly that can be readily inserted or removed from slot 14. This assembly is suitably rigidly secured in slot 14 as by means of a plurality of bolts 54 which extend through bores 56 in block 2 and thread into cooperating bores 58 in the upper and lower plate members, respectively.

Transducer 64 which is mounted on the sensing block 2 is suitably electrically connected to one branch of an adjustable bridge circuit 72 by suitable conductors 74, 76 and brush-slip ring contact means generally indicated at 78, as shown in FIGURE 5. The exciting current for the circuit is supplied from a suitable source such as a 2000 c.p.s. oscillator through conductors 80' and 82 to a variable adjustable bridge circuit 72 used for accurately adjusting the null and sensitivity of the bridge circuit. The output of the bridge is electrically connected to a transformer 84 by conductors 86 and 88. Transformer 84 is suitably electrically connected to a filter 90 by conductors 92 and 94 which in turn is suitably electrically connected to an oscilloscope 96 by conductors 98 and 100.

In operation, as cutting loads are applied to the cutter bit by the resistance of the earth strata the resulting forces are transmitted to the upper portion 20 of block 2 causing a bending moment about a fulcrum atthe left end of slot 14 resulting in a deflection of portion 20 relative to lower portion 22 of block 2. As the space between transducer face 65 and the upper portion 20 of block 2 is decreased and increased, the vibrations and fluctuations of such upper portion are transmitted to transducer 64 which converts mechanical movements of upper portion 20 into electrical impulses. These impulses are transmitted through an electrical circuit to an oscilloscope for translating such electrical impulses into visual signals as shown in FIGURE 6.

As shown in FIGURE 6, the righthand or B portion of the oscillograph illustrates the signal received when no stops are employed. The relative amplitudes of such signals are proportional to the relative forces applied to the bit. Since the forces acting on a cutter bit resulting from rock are approximately ten times as great as coal, the amplitude of rock indication is ten times that of coal. Because of the small radial extent of the signal, it is diflicult to distinguish between coal and fire clay which have similar hardness properties. On the other hand, if the device were adjusted to enlarge the signal for coal and fire clay, the amplitude of rock indication could not be contained on the screen.

To provide for a larger signal of coal and clay and thereby a more sensitive indication and still contain the rock signal on the screen, it was found desirable to restrain the deflecting motion of upper portion 20 by stiffening said upper portion through the use of stops 38, 41, 44 and 48. As loads on the cutter bit increase, stops 38 and 41 engage, thus shortening the moment arm of upper portion 20. Thus, as cutter bit pressure increases the rate of deflecting motion change of upper portion 20 is decreased and reproduced as such on the screen. By way of comparison, when rock is encountered, which is substantially ten times as hard as coal, upper portion 20 will deflect about stops 38 and 41 causing surface 25 to move a distance approximately twice as far as in the case of coal contact. It is to be noted that the amplitude of rock deflection as observed on the screen (see A por tion of FIG. 6) is approximately twice that of the amplitude of coal deflection. Of course, as cutting pressures on the bit further increase, stops 44 and 48 will engage, further shortening the moment arm of upper portion 20 resulting in a further decreasing rate of defleeting motion change. Any force encountered by the resistance of earth strata approximately ten times as great as rock would produce an image on the screen of approximately twice the amplitude of rock indication or four times the amplitude of coal indication. Thus, the present invention provides for three distinct rates of deflection change and accordingly three rates of. signal change.

Another important advantage of the present invention is that distinguishing characteristics between coal and fire clay can be readily observed on the oscilloscope screen as a result of enlarging the image on the screen. Coal, having a somewhat brittle characteristic, fractures out in large pieces so that momentarily during cutter bit rotation, no strata is encountered, resulting in a signal which is erratic in both amplitude and frequency. Fire clay, which is more pliable than coal and therefore more consistant produces a signal having an amplitude determined by the depth of cut with a constant frequency. As shown in the A portion of FIG. 6, the image of fire clay deflection reproduced on the screen is substantially fixed in radial extent and recognizably different from the coal image. Thus, because the stops allow the device to be adjusted to enlarge the image of coal and fire clay indication, a more reliable and marked distinction between coal and clay is obtained as shown in the A portion of FIG. 6.

A preferred embodiment of the principles of this invention having been hereinabove described and allustrated, it is to be realized that variations in design may be applied without departing from the broad spirit and scope of this invention. It is therefore respectfully requested that this invention be interpreted as broadly as possible and be limited only by the prior art.

We claim:

1. A strata sensing device comprising: a housing having portions adapted to move relative to each other; strata engaging means carried by one of said portions; means carried by said housing for sensing relative movement between said portions; and means carried by said housing and engagable with at least one of said portions after a predetermined relative movement therebetween has occured for varying the rate of further relative movement between said portions which further relative movement would be capable of being sensed by said sensing means.

2. A strata sensing device comprising: a housing having portions adapted to move relative to each other; a strata engaging means carried by one of said portions; means carried by said housing for sensing relative movement between said portions; and means carried by said housing and engagable with at least one of said portions after a predetermined relative movement therebetween has occured for decreasing the rate of further relative movement between said portions which further relative movement would be capable of being sensed by said sensing means.

3. A strata sensing device comprising: a housing having portions adapted to move relative to each other; strata engaging means carried by one of said portions and responsive to applied loads for imparting a movement thereto; means carried by said housing for sensing relative movements between said portions; and means carried by said housing and engagable with at least one of said portions after a predetermined relative movement therebetween has occured for decreasing the rate of further relative movement between said portions in relation to applied loads which further relative movement would be capable of being sensed by said sensing means.

4. A strata sensing device comprising a housing having two portions, a strata engaging means mounted in one of said portions for imparting strata-hardness responsive movement to said one portion about a fulcrum point, means for changing the fulcrum point about which said one portion moves to vary the amount of movement per unit load applied, and means carried by said other portion for sensing such movement.

5. A strata sensing device as defined by claim 4 in which the means for changing the fulcrum point about which said one portion moves comprises at least a pair of stops, said stops having complementary engaging surfaces located between said two portions.

6. A strata sensing device comprising a housing having two elongated laterally spaced arms defining a slot therebetween extending across the entire width of said housing and inwardly from one end of said housing parallel to the longitudinal axis thereof, a strata engaging means mounted in one of said arms extending outwardly therefrom and normal to the longitudinal axis of said housing, said strata engaging means imparting strata responsive movement to said one arm toward the other of said arms, means for limiting the movement of said one arm and changing the fulcrum point about which said one arm moves to vary the amount of such movement per unit load applied, and an electrical transducer at least partially carried by the other of said arms for sensing such movement.

7. A strata sensing device comprising: a housing having two elongated laterally spaced arms defining a slot therebetween; a strata engaging means mounted in one of said arms and responsive to forces applied for imparting movement to said one arm toward the other of said arms; means located in said slot and engageable with said arms upon relative movement therebetween for varying the amount of relative movement of said arms per unit load applied; an electrical transducer carried at least partially by the other of said arms for sensing the relative movement between said arms; and said means for varying the amount of movement between said arms comprising two pairs of stops having complementary opposed surfaces, respectively.

3. A strata sensing device comprising: a housing havtherebetween; a strata engaging means mounted in one of said arms and responsive to forces applied for imparting movement to said one arm toward the other of said arms; means located in said slot and engageable with said arms upon relative movement therebetween for varying the amount of relative movement of said arms per unit load applied; an electrical transducer carried at least partially by the other of said arms for sensing the relative movement between said arms; said means for varying the amount of movement between said arms comprising at least a pair of stops having complementary opposed surfaces; each of said arms being provided with a plate releasably secured thereto; each plate having at least one depression thereon to receive one of said pair of stops; and one of said plates having a transverse bore to receive at least a portion of said transducer.

9. A strata sensing device comprising: a housing having two elongated laterally spaced arms defining a slot therebetween; a strata engaging means mounted in one of'said arms and responsive to forces applied for impart- 'mg two elongated laterally spaced arms defining a slot ing movement to said one arm toward the other of said arms; means located in said slot and engageable with said arms upon relative movement therebetween for varying the amount of relative movement of said arms per unit load applied; an electrical transducer carried at least partially by the other of said arms for sensing the relative movement between said arms; said means for varying the amount of movement between said arms comprising at least a pair of stops having complementary opposed surfaces; each of said arms being provided with a plate releasably secured thereto; each plate having at least one depression thereon to receive one of said pair of stops; one of said plates having a transverse bore to receive at least a portion of said transducer; and means provided in said slot for sealing said slot and said stops and a portion of said transducer therein against the entrance of water and other foreign matter.

It A strata sensing device comprising: a housing having two elongated laterally spaced arms defining a slot therebetween extending across the entire width of said housing and inwardly from one end of said housing parallel to the longitudinal axis thereof; a strata engaging means mounted in one of said arms extending outwardly therefrom and normal to the longitudinal axis of said housing; said strata engaging means imparting strata responsive movement to said one arm toward the other of said arms; means for limiting the movement of said one arm and changing the fulcrum point about which said one arm moves for varying the amount of such movement per unit load applied; an electrical transducer at least partially carried by the other of said arms for sensing such movement; said means for changing the fulcrum point about which said one arm moves comprising at least a pair of stops; and said stops having complementary engaging surfaces.

11. A strata sensing device comprising: a housing having two elongated laterally spaced arms defining a slot therebetween extending across the entire width of said housing and inwardly from one end of said housing parallel to the longitudinal axis thereof; a strata engaging means mounted in one of said arms extending outwardly therefrom and normal to the longitudinal axis of said housing; said strata engaging means imparting strata responsive movement to said one arm toward the other of said arms; means for limiting the movement of said one arm and changing the fulcrum point about which said one arm moves for varying the amount of such movement per unit load applied; an electrical transducer at least partially carried by. the other of said arms for sensing such movement; said means for changing the fulcrum point about which said one arm moves comprising two pairs of stops; each pair of stops having complementary engaging surfaces; each arm being provided with a plate releasably secured thereto; each plate having a plurality of depressions thereon to receive said stops; and one of said plates having a transverse bore to receive at least a portion of said transducer.

12. A strata sensing device comprising: a housing having portions adapted to move relative to each other; strata engaging means carried by one of said portions; means carried by said housing for sensing relative movements between said portions; and means comprising at least one pair of stop members carried by one of said portions and engageable with the other of said portions upon a predetermined relative movement therebetween for decreasing the rate of further relative movement therebetween.

13. A strata sensing device comprising: a housing having portions adapted to move relative to each other; strata engaging means carried by one of said portions and responsive to applied loads for imparting a movement thereto; means carried by said housing for sensing relative movements betweensaid portions; and means comprising at least one pair of stop members carried by one of said portions and engageable with the other of said portions upon a predetermined relative movement therebetween for decreasing the rate of further relative movement therebetween in relation to applied loads.

14. A strata sensing device comprising: a housing comprising two portions having a first rate of deflection relative to each other; strata engaging means carried by one of said portions; means carried at least partially by one of said portions for sensing a relative movement between said portions; and means comprising at least one pair of stop members carried by one of said portions and en gageable with the other of said portions upon predetermined relative movement therebetween for obtaining a second rate of deflection therebetween.

15. A strata sensing device for a mining machine comprising: a cutter arm member; a housing member carried on the outer reach of said arm member, said housing member having portions adapted to move relative to each other; strata engaging means carried by one of said portions; means carried by said housing for. sensing relative movement between said portions; and means carried by one of said members and engageable with at least one of said portions after a predetermined relative movement therebetween has occurred for varying the rate of further relative movement between said portions which further relative movement would be capable of being sensed by said sensing means.

16. A strata sensing device for a mining machine comprising: a cutting arm member; a housing member carried on the outer reach of said arm member, said housing member having portions adapted to move relative to each other; strata engaging means carried by one of said portions; means carried by said housing for sensing relative movement between said portions; and means carried by one of said members and engageable with at least one of said portions after a predetermined relative movement therebetween has occurred for decreasing the rate of further relative movement between said portions which further relative movement would be capable of being sensed by said sensing means.

17. A strata sensing device for a mining machine comprising: a cutting arm member; a housing member carried on the outer reach of said arm member, said housing member having portions adapted to move relative to each other; strata engaging means carried by one of said portions; means carried by said housing for sensing relative movement between said portions; and means carried by one of said members and engageable with at least one of said portions after a predetermined relative movement therebetween has occurred for decreasing the rate of further relative movement between said portions in relation to applied loads which further relative movement would be capable of being sensed by said sensing means.

References Cited by the Examiner UNITED STATES PATENTS 336,641 2/1886 Hallock 177236 X 2,752,591 6/1956 Felbeck et al. 340261 9/1964 Heimaster et al. 73-78 I. W. MYRACLE, Assistant Examiner. 

1. A STRATA SENSING DEVICE COMPRISING: A HOUSING HAVING PORTIONS ADAPTED TO MOVE RELATIVE TO EACH OTHER; STRATA ENGAGING MEANS CARRIED BY ONE OF SAID PORTIONS; MEANS CARRIED BY SAID HOUSING FOR SENSING RELATIVE MOVEMENT BETWEEN SAID PORTIONS; AND MEANS CARRIED BY SAID HOUSING AND ENGAGABLE WITH AT LEAST ONE OF SAID PORTIONS AFTER A PREDETERMINED RELATIVE MOVEMENT THEREBETWEEN HAS OCCURED FOR VARYING THE RATE OF FURTHER RELATIVE MOVEMENT BETWEEN SAID PORTIONS WHICH FURTHER RELATIVE MOVEMENT WOULD BE CAPABLE OF BEING SENSED BY SAID SENSING MEANS. 